replay: introduce block devices record/replay

This patch introduces block driver that implement recording
and replaying of block devices' operations.
All block completion operations are added to the queue.
Queue is flushed at checkpoints and information about processed requests
is recorded to the log. In replay phase the queue is matched with
events read from the log. Therefore block devices requests are processed
deterministically.

Signed-off-by: Pavel Dovgalyuk <pavel.dovgaluk@ispras.ru>
[ kwolf: Rebased onto modified and already applied part of the series ]
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/stubs/replay.c b/stubs/replay.c
index 2f1a6dc62e..de9fa1ec98 100644
--- a/stubs/replay.c
+++ b/stubs/replay.c
@@ -63,3 +63,7 @@ void replay_char_read_all_save_buf(uint8_t *buf, int offset)
 {
     abort();
 }
+
+void replay_block_event(QEMUBH *bh, uint64_t id)
+{
+}